This application relates to a shaft used to interconnect a motor and drive mechanism in a seat assembly. Specifically, the shaft includes helical end portions that are twisted with respect to mating connectors to create an interference fit.
Seat adjusters are used to adjust the position of a vehicle seat between various positions. Typically, seat adjusters use electric motors to move a certain seat member between a plurality of positions. The motors are used to power a drive mechanism that is operably connected to the seat member. Most seat adjusters use a flexible shaft or cable to transmit a torsion load from the motor to the drive mechanism. Both ends of the shaft are usually the same to allow for easy assembly of the shaft to the motor and drive mechanism, i.e., assembly of the shaft into the seat adjuster is insensitive to shaft orientation. To further ease assembly, the connectors that receive the ends of the shaft are designed to have the same shape as the ends.
It is common for both ends of the shaft to have a square cross section and for the connectors that receive the ends to have a corresponding square aperture. The shaft ends are typically referred to as male members and the connectors that receive the ends are typically referred to as female members. The square ends of the male members are inserted into the square apertures of the female members to form an interconnect interface. The apertures in the female members are slightly larger than the ends of the male members so that the male members can be easily connected to the female members. The performance of this interface can vary significantly because both the male and female members are square in shape and have respective manufacturing tolerances. Further, because the apertures in the female members are larger than the ends of the male members, there can be looseness between the mating components. This is undesirable because an audible clicking is produced when the shaft is rotating.
Coatings can be used to reduce the clicking noise, however, this adds cost and requires an additional assembly step. Thus, it is desirable to provide an improved interface between the shaft and the connectors for the motor and drive mechanism that eliminates noise during operation. The shaft should also be easily installed onto the motor and drive mechanism and allow for blind assembly.